中文摘要：

使用密度泛函方法在UB3LYP／6-311＋＋G（3df,2p）水平上对自由基环化合成β-内酰胺的四种反应途径进行理论研究．结合Marcus理论对影响反应的热力学及动力学因素进行分析，发现氨基甲酰基自由基4-exo环合反应是理想的动力学控制过程；酰胺自由基的4-exo环合反应与5-endo环合反应相比是动力学有利的转化过程；单取代的酰胺烷基自由基的4-exo环合反应是一类动力学和热力学都较为不利的反应；羰基自由基加成亚胺N=C双键的4-exo环合反应与5-endo环合反应相比动力学不利而热力学有利．

英文摘要：

The preparation of β-lactams through four different radical cyclization reactions was studied by density functional theory calculations at the UB3LYP/6-311 ＋＋G（3df, 2p） level. Thermodynamics and kinetics of these radical cyclizations were analyzed using the Marcus theory. The calculated results showed that the 4-exo cyclization of carbamoyl radical was an ideal kinetic-control process. The 4-exo cyclization of carbamoylalkyl radical was predicted to be kinetically competitive with the 5-endo process. The 4-exo cyclization of amido radical was less favorable both kinetically and thermodynamically. Finally, the 4-exo ring closure of an acyl radical onto an imine acceptor was thermodynamically competitive with the 5-endo process but less favorable kinetically.